Hope and change is just a slogan means nothing. He's a centrist and always presented himself as one
in 2008 he was pretty liberal. he had a reputation as a liberal senatorObama very much campaigned as a liberal. His opponents ran ads of him being a radical. The difference between him and other dems. Is he was able to define himself instead of being afraid of others doing so. Hilary ran a trash campaign and barely visited the state supposedly.
on foreign policy especially he was considered liberal because of his opposition to the War in Iraq. that strongly helped him
one of the first things he did as president was try to close Guantanamo Bay. he and the dems were also ready for a public option before Joe Lieberman ruined all of that.
now he wasn’t as far to the left as someone like sanders or warren by any means. and his messaging and campaign strategy was inclusive and moderate but compared to kerry, gore and the other democratic candidates in 2008 he was definitely more liberal
what santorum probably wouldn’t realize or want to admit is after eight years of Bush the country - and Pennsylvania - was much more ready to elect a liberal president. and what we think of as liberal in 2020 is very different from what they thought in 2008